Tissue systems - College of Charleston

Tissue systems - College of Charleston

Lecture #4 Plant Structure, Growth And Development Image the Angel Oak 1 Key Concepts:

What is a kingdom? Why study plants? What makes a plant a plant? The hierarchy of structure plant cells, tissues and organs Growth

Primary growth elongation Secondary growth diameter expansion Morphogenesis occurs during growth 2 Carolus Linnaeus (1707-1778) Image Linnaeus

The founder of modern taxonomy defined kingdoms by morphological similarity 3 Linnaeus Taxonomic Hierarchy Taxonomic Category Example (taxon)

Kingdom Plantae, also Metaphyta = all plants Division (phylum) Magnoliophyta = all angiosperms Class

Liliopsida = all monocots Order Asparagales = related families (Orchidaceae, Family Orchidaceae = related genera (Platanthera, Genus

Platanthera = related species (P. ciliaris, P. Specific name/epithet ciliaris = one species Iridaceae, etc) Spiranthes, etc) integra, etc)

4 Linnaeus Taxonomic Hierarchy Taxonomic Category Example (taxon) Kingdom Plantae, also Metaphyta = all plants

Division (phylum) Magnoliophyta = all angiosperms Class Liliopsida = all monocots Order

Asparagales = related families (Orchidaceae, Family Orchidaceae = related genera (Platanthera, Genus Platanthera = related species (P. ciliaris, P. Specific name/epithet

ciliaris = one species Iridaceae, etc) Spiranthes, etc) integra, etc) 5 Images the yellow fringed orchid

Platanthera ciliaris 6 Linnaeus recognized only 2 kingdoms If it moved animal; if it didnt plant Fungi were lumped with plants The microscopic world was largely unknown Images the 3 multicellular kingdoms, animals, fungi and plants

7 The 5 kingdom system developed in the 1960s and used until recently Diagram the 5 kingdom system 8 Molecular data supports 3 domain

classification scheme Diagram 3 domain system of classification Kingdoms are defined by monophyletic lineage 9 Classification is Dynamic! Diagram transition from 5 kingdom to 3 domain system indicating dynamic nature of classification Multicellular eukaryotes remain fairly well defined

the plants, fungi and animals. Classification of single celled organisms is still underway. 10 Current Taxonomic Hierarchy Taxonomic Category Example (taxon) Domain

Eukarya = all eukaryotic organisms Kingdom Plantae, also Metaphyta = all plants Division (phylum) Magnoliophyta = all angiosperms Class

Liliopsida = all monocots Order Asparagales = related families (Orchidaceae, Family Orchidaceae = related genera (Platanthera,

Genus Platanthera = related species (P. ciliaris, P. Specific name/epithet ciliaris = one species Iridaceae, etc) Spiranthes, etc)

integra, etc) 11 Why Plants? 12 Why Plants? Image shooting stars

13 What makes a plant a plant??? 14 Images and diagrams characteristics that separate plants from other kingdoms 15

What makes a plant a plant??? Multicellular, eukaryotic organisms with extensive specialization Almost all are photosynthetic, with chloroplasts (= green) Some obtain additional nutrition through parasitism or carnivory Some are saprophytic, entirely without chlorophyll (absorb dead OM) Excess carbohydrates stored as starch (coiled, branched polymer of glucose) Cell walls of cellulose = fibrous (not branched)

polysaccharide = accounts for the relative rigidity of the cell wall Cell division by formation of cell plate Most extant plant species are terrestrial (many characteristics that are adapted for terrestrial life) Separated from cyanobacteria by chloroplasts Separated from green algae by various adaptations to 16 terrestrial life Read this later. Plants were the first organisms to

move onto land Occurred about 475mya Very different conditions from former marine habitat Many new traits emerged in adaptation to life on dry land Extensive adaptive radiation into many new ecological niches 17 Four major

groups of plants have emerged since plants took to land Diagram phylogeny of land plants; same on next slide 18 We will focus

on angiosperms Next semester in 211 you will learn more about the transition from water to land, and the evolution of reproductive strategies in all plants

19 Angiosperms the flowering plants: 90% of the Earths modern flora Images flowering plants 20 Basic Structure of the Plant Cell whats unique???

Diagram plant cell; same on next slide 21 Basic Structure of the Plant Cell 22 Critical Thinking Do all plant cells have chloroplasts??? How can you tell???

23 Critical Thinking Do all plant cells have chloroplasts??? How can you tell??? 24 Critical Thinking Do all plant cells have

chloroplasts??? How can you tell??? Image chloroplast free white bracts on white-top sedge 25 More on the cell wall: All cell walls are produced by the cell

membrane, outside Primary wall is produced first Diagram primary and secondary cell walls; same on next slide Mostly cellulose Secondary walls are produced later

Lignified, so ??? Secondary walls are interior to primary walls 26 More on the cell wall: All cell walls are produced by the cell

membrane Primary wall is produced first Mostly cellulose Secondary walls are produced later Lignified, so Secondary walls are interior to primary

walls 27 Five Major Plant Cell Types Micrographs plant cell types Parenchyma

Collenchyma Sclerenchyma Xylem elements Phloem elements 28 Parenchyma

Thin primary wall No secondary wall Many metabolic and storage functions Bulk of the plant body Micrographs parenchyma cells 29 Collenchyma

Thick primary wall No secondary wall Micrograph collenchyma cells; same on next slide Implications??? Support growing

tissues 30 Collenchyma Thick primary wall No secondary wall Implications??? Support growing

tissues 31 Sclerenchyma Thick secondary wall Secondary walls are lignified Micrograph sclerenchma cells; same on next slide

Implications??? Support mature plant parts Often dead at maturity 32 Sclerenchyma Thick secondary wall Secondary walls are lignified

Implications??? Support mature plant parts Often dead at maturity 33 Collenchyma vs. Sclerenchyma

Both provide structural support Both have thick walls Collenchyma = thick primary wall, no lignin Sclerenchyma = thick secondary wall, lignified Micrographs collenchyma and sclerenchyma cell comparison 34 Xylem Elements

Lignified secondary walls Always dead at maturity (open) Function to transport water and dissolved nutrients, and to support the plant Tracheids and vessel elements

Diagrams and micrograph tracheids and vessel elements 35 Critical Thinking Vessel elements and the convergent evolution of rings What else looks like

this???? What is the function???? Micrograph rings of lignin in developing vessel element; same on next slide 36 Critical Thinking

Vessel elements and the convergent evolution of rings What else looks like this???? What is the function???? 37 Phloem Elements

Sieve tube members + companion cells STM lack nucleus, ribosomes their metabolism is controlled by the companion cells Micrograph phloem elements Function to transport the products of metabolism

Non-angiosperms have more primitive phloem elements 38 Critical Thinking What might be the functional advantage of a cell with no nucleus??? Diagram phloem elements

39 Critical Thinking What might be the functional advantage of a cell with no nucleus??? 40 Plants are Simple Only Five Major

Cell Types Micrographs plant cell types Parenchyma Collenchyma Sclerenchyma Xylem elements Phloem elements 41

Tissue Systems Diagram plant tissue types Epidermis

Vascular Ground Meristem 42 Epidermis Tissue: Covers the outer surface of all plant parts Shoot surfaces covered with waxy cuticle

Micrograph and diagram epidermis Helps to protect the plant and prevent desiccation Usually a single, transparent cell layer Tight joints; stomata allow for

gas exchange 43 Critical Thinking Do roots have a waxy cuticle??? Why or why not??? 44 Critical Thinking Do roots have a waxy cuticle??? Why or why not???

Never forget the importance of natural selection!!!!! 45 Vascular Tissue: Transports water, solutes, and metabolic products throughout the plant Confers structural support

Includes xylem elements, phloem elements, parenchyma and sclerenchyma fibers Micrograph vascular bundle in cross section 46 Critical Thinking

Why does vascular tissue give structural support to a plant??? 47 Critical Thinking Why does vascular tissue give structural support to a plant??? 48

Ground Tissue: Bulk of the plant body pith, cortex and mesophyll Mostly parenchyma Most metabolic, structural and storage functions Micrograph and diagram ground tissues in stems and leaves

49 Critical Thinking Is this what the inside of a tree looks like??? Micrograph herbaceous dicot stem 50 Critical Thinking

Is this what the inside of a tree looks like??? Micrograph of herbaceous eudicot stem; image of woody stem; diagram of woody stem tissue organization 51 Meristem Tissue: How the plant grows Cells divide constantly during the growing

season to make new tissues More details later Image new growth at tip of stem 52 Plants are Simple Only Four Major Tissue Types

Diagram plant tissue systems Epidermis Vascular Ground Meristem 53

Tissues Make Organs: Roots anchor the plant, absorb water and nutrients Stems support the leaves Leaves main site of photosynthesis Reproductive organs (flowers, cones, etc more later) All organs have additional functions hormone synthesis, transport, etc 54

Plant Organ Systems Diagram root and shoot systems 55 Modern molecular evidence indicates four classes of angiosperms paleoherbs magnoliids

eudicots monocots ancestral 56 Paleoherbs and Magnoliids comprise about 3% of angiosperms Paleoherbs

Aristolochiaceae, Nymphaeaceae, etc Magnoliids Magnoliaceae, Lauraceae, nutmeg, black pepper, etc Images water lily and magnolia 57

Modern evidence indicates 4 classes of angiosperms paleoherbs magnoliids eudicots monocots ~ 97% of

angiosperms ancestral 58 Monocots include grasses, sedges, iris, orchids, lilies, palms, etc.. Images monocots 59

Eudicots include 70+% of all angiosperms: Most broadleaf trees and shrubs Most fruit and vegetable crops Most herbaceous flowering plants Images eudicots 60 Monocots vs. Eudicots

Monocots Flower parts in multiples of 3 Parallel leaf venation Single cotyledon Vascular bundles in complex arrangement ~90,000 species Eudicots Flower parts in multiples

of 4 or 5 Netted leaf venation Two cotyledons Vascular bundles in a ring around the stem Modern classification indicates 2 small primitive groups + eudicots 200,000+ species 61

Root System Tissue Organization Eudicots Monocots Micrographs cross sections of eudicot and moncot roots; same on next 3 slides Epidermis, ground, endodermis, pericycle, vascular tissues

62 Eudicot root closeup Epidermis Cortex Endodermis Pericycle Vascular tissues in solid core

63 Monocot root closeup Epidermis Cortex Endodermis Pericycle Vascular tissues in ring Pith in the very center

64 Critical Thinking Where do branch roots form??? 65 Critical Thinking Where do branch roots form??? Micrograph root emerging from pericycle

66 Stem System Tissue Organization Eudicots Monocots Micrograph eudicot and monocot stem tissue organization; same on next 4 slides

Epidermis, ground, vascular tissues 67 Eudicot stem closeup Epidermis Cortex Vascular tissues bundles in a ring

Pith 68 Monocot stem closeup Epidermis Cortex Vascular tissues bundles are scattered

69 Wood forms from a meristem that links the vascular bundles: 70 Stem System Tissue Organization Eudicots Monocots

Monocots cannot make wood More on wood formation later 71 Leaf Tissue Arrangement Micrograph cross-section of leaf tissue arrangement Epidermis, ground, vascular tissues 72

Leaf closeup Epidermis Diagram leaf tissue arrangement Cortex palisade mesophyll Cortex spongy mesophyll

Vascular tissues 73 Stomata pores to allow for gas exchange and transpiration Micrograph epidermis tissue showing stomata 74

See, plants really are simple 5 cell types 4 tissue types 4 organ types Diagram shoot and root systems 75 Plant Growth Remember, most plants are anchored by

roots They cant move to escape or take advantage of changes in their environment Plants adjust to their environment Simple structure + lots of developmental flexibility allow plants to alter when and how they grow Developmental flexibility comes from meristems 76

Meristem Tissues Actively dividing cells that generate all other cells in the plant body Cause indeterminate growth Stems and roots elongate throughout the plants life (indeterminate primary growth) Trees continually expand in diameter (indeterminate secondary growth) Branches form in roots and stems

77 Not all plant parts have indeterminate growth patterns Indeterminate: Roots and Stems Determinate: Leaves

Flowers Fruits These parts grow throughout the life of the plant, exploring new environments or responding to damage These parts grow to a

genetically +/predetermined size and shape and then stop cannot repair 78 damage Some mature cells can de-differentiate to become meristematic once more!!! Primarily occurs in the indeterminate parts Stems and roots

A process that very seldom occurs in other kingdoms Allows stems and roots to repair damage and form branches and sprouts 79 Critical Thinking Can all plant cells de-differentiate??? What would control this???

80 Critical Thinking Can all plant cells de-differentiate??? What would control this??? 81 Critical Thinking Can all plant cells de-differentiate???

What would control this??? 82 Growth in Plants: an irreversible increase in size due to metabolic processes (processes that use ATP energy) Cell division produces new cells = function of meristem Cell expansion increases the size of the

new cells = up to 80% of size increase Cell differentiation occurs during and after expansion 83 The plane of cell division contributes to morphogenesis Diagram planes of cell division and the effect on morphogenesis Division in 2 planes forms sheets of cells 84

Critical Thinking What tissues are files of cells??? What tissues are sheets of cells??? What tissues are 3-D bulky??? 85 Critical Thinking What tissues are files of cells??? What tissues are sheets of cells??? What tissues are 3-D bulky???

86 Growth in Plants: an irreversible increase in size due to metabolic processes (processes that use ATP energy) Cell division produces new cells = function of meristem Cell expansion increases the size of the new cells = up to 80% of size increase

Cell differentiation occurs during and after expansion 87 Auxin-mediated cell expansion Diagram how auxin works to promote cell expansion ATP is used 88 The direction of cell expansion depends on cellulose

orientation, and contributes to morphogenesis Diagram cellulose orientation in primary wall and the effects on morphogenesis 89 Growth in Plants: an irreversible increase in size due to metabolic processes (processes that use ATP energy)

Cell division produces new cells = function of meristem Cell expansion increases the size of the new cells = up to 80% of size increase Cell differentiation occurs during and after expansion 90 Expansion and differentiation occur in an

overlapping zone in all plant parts Diagram patterns of growth in roots 91 REVIEW: Growth in Plants: an irreversible increase in size due to

metabolic processes (processes that use ATP energy) Cell division produces new cells = function of meristem Cell expansion increases the size of the new cells = up to 80% of size increase Cell differentiation occurs during and after expansion 92 Location of the

meristems determines the pattern of plant growth Diagram location of meristems on the plant body; next slide also Most common meristems:

apical, axillary and lateral 93 Apical meristems cause elongation of roots and stems

94 Micrograph longitudinal section showing distribution of tissues in root 95 Images root cap and mucigel 96 Root Cap

Protects the meristem Secretes mucigel Eases movement of roots through soil Secretes chemicals that enhance nutrient uptake Constantly shedding cells Mechanical abrasion as roots grow through soil Constantly being replenished by meristem

97 Primary Growth in Roots Diagram longitudinal section of root showing zones of growth; same on next 2 slides 98 Primary Growth in Roots 99

Primary Growth in Roots 100 Root Hairs Form as the epidermis fully differentiates Extensions off epidermal cells NOT files of cells

Part of an epidermal cell Micrograph root hairs extending from epidermis; same on next few slides Hugely increase the surface area of the epidermis 10 cubic cm (double handful) of soil might contain 1 m of plant roots

Mostly root hairs 101 Critical Thinking What is the selective advantage of root hairs??? 102 Critical Thinking

What is the selective advantage of root hairs??? 103 Root Hairs By contrast, 10 cc of soil may contain up to 1000 m of fungal hyphae (1km!) These serve a similar function for the fungus

Ramify throughout the substrate for maximum absorption Some fungi form symbiotic associations with plant roots and both organisms benefit from this huge absorptive surface area! More in 211.. 104

Apical meristems cause elongation of roots and stems Diagram location of apical meristems 105

Apical Meristems in Shoots Micrograph longitudinal section of stem showing apical and axillary meristems 106 Critical Thinking There is no shoot cap why not???

107 Critical Thinking There is no shoot cap why not??? 108 Axillary meristems allow for

branching similar in structure and function to apical meristems Diagram meristem locations Remember, pericycle in roots has same function

109 Axillary Meristems in Shoots Micrograph longitudinal section of stem showing apical and axillary meristems; same on next two slides 110

Primary Growth in Shoots Apical meristem Leaf primordia Axillary buds 111 As with roots cell division occurs first; zones of expansion and differentiation

overlap Axillary buds may activate to make branches, or may remain dormant 112 Primary growth of a shoot elongation from the tip Diagram how stems elongate during primary growth

113 Lateral meristems cause diameter expansion Diagram meristem locations Roots also expand

in diameter, but its more complicated well save that for BIOL 300 114 Lateral Meristems = Cambiums Diagram lateral meristems 115

Remember: Diagram primary vs. secondary growth Elongation is primary growth Diameter expansion is secondary growth 116

Secondary growth diameter expansion Images cross section of wood and whole tree 117 Eudicot Stem recall the arrangement of vascular bundles

Micrograph cross section of a eudicot stem; same on next 2 slides 118 Eudicot Stem recall the arrangement of vascular bundles Vascular cambium forms here:

119 Eudicot Stem recall the arrangement of vascular bundles Vascular cambium forms here: a cylinder of meristem tissue between

the xylem to the interior and the phloem to the exterior 120 Secondary xylem and phloem form through cell division by the vascular cambium Diagram location of the vascular cambium relative to other tree tissues

121 During primary growth the vascular tissues form in bundles from the apical meristem Diagram transition from primary growth to secondary growth; same on next slide

During secondary growth the vascular tissues form in cylinders from the vascular cambium 2o xylem to the inside 2o phloem to the outside

122 Secondary xylem accumulates 123 Secondary Xylem = Wood! Micrograph cross section of woody plant

showing secondary tissues; same on next slide 124 Annual growth rings are accumulating rings of secondary xylem 125 Critical Thinking Why do eudicot trees taper???

Diagram pattern of accumulation of secondary xylem as a tree grows; same on next slide 126

Critical Thinking Why do eudicot trees taper??? 127 Bark All tissues external to the vascular cambium Diameter expansion splits original epidermis Bark structurally and functionally replaces

epidermis Inner bark Functional secondary phloem Outer bark Composition varies as tree matures 128 Bark Formation

Micrograph cross section of a tree showing bark formation 129 Cork Cambium Meristematic tissue Forms in a cylinder during 2o growth Divides to produce cork cells Cells filled with waxy, waterproof suberin Eventually cork cambium becomes cork

itself 130 More on cork cambium First layer develops from cortex De-differentiation!!! Second layer forms from cortex same process Third layer forms from cortex.. Cortex eventually runs out

Then what??? 131 More on cork cambium First layer develops from cortex De-differentiation!!! Second layer forms from cortex same process Third layer forms from cortex.. Cortex eventually runs out

Then what??? 132 More on cork cambium First layer develops from cortex De-differentiation!!! Second layer forms from cortex same process Third layer forms from cortex.. Cortex eventually runs out

Then what??? 133 More on cork cambium First layer develops from cortex De-differentiation!!! Second layer forms from cortex same process Third layer forms from cortex.. Cortex eventually runs out

Then what??? 134 Critical Thinking What is the next available layer of tissue??? Diagram lateral meristems and the secondary tissues in a tree; same on next slide 135

Critical Thinking What is the next available layer of tissue??? 136 More on cork cambium First layer develops from cortex De-differentiation!!!

Second layer forms from cortex same process Third layer forms from cortex.. Cortex eventually runs out Then what??? 137 More on cork cambium First layer develops from cortex De-differentiation!!!

Second layer forms from cortex same process Third layer forms from cortex.. Cortex eventually runs out Then what??? 138 Stem Tissue Derivations and Fates: Diagram how undifferentiated cells develop into the tissues of the plant body Cells divide, expand and differentiate

139 Review: Key Concepts:

What is a kingdom? Why study plants? What makes a plant a plant? The hierarchy of structure plant cells, tissues and organs Growth Primary growth elongation Secondary growth diameter expansion Morphogenesis occurs during growth

140 Monocots, Palmetto Trees, Ft. Moultrie and the SC State Flag Various images and a micrograph of a monocot stem an example of one influence of plants on American history 141

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